In the spraying of agricultural chemicals, it is important to minimize the double spraying of crops due to overlap off sprayer passes and also to eliminate any gaps between the sprayer passes. To enable this, systems have been developed for dropping markers, for example patches of foam, paper or chalk on a field to designate the edge of a sprayer pass. Other systems use discs that leave a mark on the ground. These systems are all subject to visibility problems, especially where spraying is being done at night, the most common time for such work because of reduced winds.
Another system which has been developed is the "tramline" system that leaves unseeded rows at appropriate intervals along a field to accommodate the tires of a tractor. While this system is effective in that it provides a reliable, highly visible and easy to follow marking in the field, the mechanisms used to achieve the desired result generally include rather complex clutching mechanisms on the drive shaft for the conventional seed flute. It may require a permanent modification of the seed metering drive shaft.
The present invention is concerned with a field marking system that is easily and simply retro-fit into any common seed drill and involves no permanent modification of the seeder.